Method of producing envelopes



Aug. 19, 1958 R. l. RAPP 2,847,915

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United States Patent M METHOD OF PRODUCING ENVELOPES Raymond I. Rapp, Philadelphia, Pa., assignor of one-half to William R. Peterson, Philadelphia, Pa.

Application December 23, 1954, Serial No. 477,317

1 Claim. (Cl. 93- -61) The object of the invention is to provide improvements in the method of producing commercial or industrial envelopes and in the resulting product, it being understood that the term envelopes applies likewise to such bags as the invention may be applicable to.

During recent years, there has developed an increasing number of entities, whether persons, firms, corporations or associations, that mail such large quantities of similar pieces of envelope mail (as distinguished from parcel post, newsprint, periodicals, and the like), that the number of pieces for a given entity runs into the millions annually, wherefore a combination of corelated details and steps in the method of production, perforation, printing, filling or stufiing, and sealing can save several dollars per thousand in labor and materials, with commensurate reduction in overhead and increased speed of handling and delivery.

Such envelope mail may comprise periodical bills, advertising matter, samples, notices, statements, reports, etc., and for a given sender seldom if ever runs the same from day to day over a monthly, quarterly, or other extended period, due to its being generally desirable to start and complete a given mailing within a given day or other relatively short period, since it is unusually desirable if not actually necessary to have it all carry the same date, and be substantially up-to-date when received.

Another object, therefore, is to provide a method of forming a simplified envelope for this particular class of work, that essentially comprises the perforation of two continuous webs to provide marginal perforations for machine sprocket feed, substantially if not actually concurrently with transverse rule-die or other suitable perforations for subsequent severance of each pair of front and rear face panels from said webs, also longitudinal lines of rule-die or equivalent perforations upon transversely opposite sides of each of said webs for the later removal of the sprocket-perforated marginal portions, and an additional line of similar perforations forstill later removal of one end of the finished envelope from and after receipt of the same by the addressee; then applying an adhesive to what will be adjacent strip-areas of each web representing the transversely opposite ends of the panels of a given envelope pair, and to one transverse edge area representing the closed bottom or lower edge of the finished product; applying 21 preferably thermosetting potential adhesive to what will be adjacent strip areas of said webs representing the top or upper edge of the finished product, that must be left open for reception of the eventual contents; then printing upon the face or front panel the name and return address of the sender, as well as a franking notice, if deisred, and also suitable indicia to indicate to the addressee the way to open the envelope when received, while upon the rear panel may be printed advertising matter if desired; then to secure the opposed adhesive strip-areas together, so as to secure each pair of envelope panels along their opposite ends and intervening bottom edge, while still in double web relationship; then addressing the front panel of each united pair Patented Aug. 19, 1958 of panels; then removing from the still attached pairs of panels the oppositely positioned sprocket-perforated marginal portions; and then severing or separating said completed envelope sections in sequence and individually from the remainder of the now composite or two-ply web; following which, either immediately thereafter, or following an indefinite intervening period, the remaining open edge of each envelope may be automatically opened and maintained so, while the filling or so-called stufling operation takes place, after which the opposed surfaces of said panels along said open edge are automatically sealed by the application of heat to said thermo-setting medium.

A further object is to provide an improved envelope for large-quantity commercial or industrial mailing, that comprises front and rear panels of substantial similar area and shape, three of their edges being secured together by suitable adhesive, while one or both of the adjacent surfaces of the fourth edge are provided with a preferably thermo-setting medium, while adjacent to but spaced from and within the adhesive area along one edge said panels are provided with registering lines of perforations, operative to aid, direct and control the removal of the adjacent marginal portion of the envelope when sealed, so as to thereafter expose and permit the removal of its contents therefrom.

Still another object is to provide a slightly modified form of the invention, which relates to the method of production and to the final product, that is commonly referred to as the penny saver or .the postage saver. In this instance, a special adhesive that never dries is applied to one internal edge or marginal area, instead of the usual glue, mucilage, or similar adhesive, or the thermo-plastic sealing medium hereinbefore referred to. This special adhesive is preferably applied only to spaced spots or abbreviated areas, in such a way that the edges normally sealed by it for and during transit can be pulled apart, so as to permit postal inspection, and rescaled by lightly pressing such edge areas together again.

And a still further object is to provide another modification of the invention, that essentially comprises the employment of initially separate front and rear panels, moistureor water-proofed throughout the full extent of their adjacent surfaces by a coating of polyethylene or equivalent substance, and heat-sealed along predetermined edges by the application of the proper critical temperature and pressure, which temperature for polyethylene is of the order of 235 325 F., and in which modification the initial open edge of the envelope may be sealed for transit by either of the methods hereinbefore referred to.

And still another object is to provide a further modified method, that comprises an initial single web of double-envelope width, completely perforating and sprocket punching the same, printing as desired, applying one or more types of adhesive as hereinafter referred to, folding to single-envelope width, then securing as by gluing along certain edges, addressing, bursting, stuffing and scaling for mailing, as hereinafter referred to in detail.

With the objects of the invention thus set forth, the invention comprises further details of construction and arrangement, such as are fully described in the following specification, when read in conjunction with the accompanying drawings, in which Fig. l is a diagrammatic view illustrating the progress of a single plane web of paper, or other suitable material from its original roll through the successive stages or steps by which it is perforated for sprocket control and for severance as hereinafter described, and then printed and piled in fanfold arrangement; Fig. 2 is a plan view of the perforating roll per se; Fig. 3 is a view similar to Fig. 1, but showing the passage of the .web, first as it is perforated and then printed if desired for advertising or other such purposes; Fig. 4 is a diagrammatic view illustrating the progress of both the frontal web of Fig. 1 and the rear web of Fig. 3 simultaneously through the concurrent application of ordinary or other equivalent adhesive to the normal bottom and opposite end edges of the eventual frontal panels that comprise the first-mentioned web, and a thermosetting adhesive to the normal upper edges of the eventual rearward panels that comprise the second web, following which said webs are united throughout the strip-areas covered by said first-mentioned adhesive; Fig. 5 is a plan view of the ordinary adhesive applying roll; Fig. 6 is a plan view of the thermosetting adhesive applying roll; Fig. 7 shows the resulting double web of Fig. 4 passing through an addressing machine; Fig. 8 shows the automatic subsequent separation of the sprocket-perforated marginal strips therefrom; Fig. 9 shows the addressed envelope sections of the series web of Fig. 8 being separated or bursted to produce in final form the individual envelopes prior to filling or stufiing; Fig. 10 is a plan view of a single such envelope into which a stiif tongue has been inserted to hold down the free edge of the rear panel of the envelope while being stuffed; Fig. 11 is an edge elevation of the same as held open by pneumatic suction means; Fig. 12 shows the filled envelopes being heatsealed along their heretofore open upper edges; Fig. 13 shows an envelope passing edgewise in its own plane between an upper heat roll and a lower platten roll; Fig. 14 shows how after the envelope is received by addressee, its contents can be exposed and removed by first removing from one end the separable marginal edge strip provided for that purpose; Fig. 15 is a diagrammatic view showing a modified method by which a thermosetting adhesive is first applied to all adhesive strip areas of one of said webs, rather than a combination of ordinary and thermoplastic adhesives, uniting the adjacent surfaces of said webs, and then heat-sealing those portions only of the potentially adhesive strip areas, necessary to securely unite the normal bottom and opposite end edges of complementary panels to form the complete envelope, to which the usual printing and other subsequent steps may be added; Fig. 16 is an elevation of the thermosetting adhesive applying roll and associated reservoirs and rolls for producing the penny-saver or postage-saver envelopes referred to and hereinafter more fully described; Fig. 17 is a plan view of the finished envelope (short of printing) having a corner of its frontal panel removed to show the spaced adhesive spots of this last-mentioned modification; Fig. 18 is a similar view showing the same envelope after the sprocket-perforated selvage has been removed; Fig. 19 is a diagrammatic view showing a modified method of producing an envelope of this general nature, in which the adjacent surfaces of a pair of webs while still separate are coated with a suitable thermoplastic medium that will insure them being moisture and waterproof, and in which method the marginal portions of this coating are heated to seal first the opposite ends and bottom of each envelope unit, and later the open top edges of the finished envelope for mailing, after it has been addressed and filled or stuffed in the manner herein described for other modifications; Fig. 20 shows how the unsealed open top of an individual envelope is run be tween an electrically heated roll and a platten roll to seal the same for mailing; Fig. 21 is a side elevation of the same; Fig. 22 is a side elevational view showing diagrammatically a further modification in which a single web or twice the transverse width of the finished envelope is perforated, folded transversely upon a central fold line of perforations and then treated as described for certain of the other modified forms of the improved envelope; and Fig. 23 is an enlarged plan view of the double-width web before and after being transversely folded.

Referring to Figs. 1 to 3, a plane web 1 is shown as unwinding from its original roll 2, and passing beneath an idler 3 towards and between a pair of suitable perforating rolls 4 and 5, by which are provided in said web oppositely positioned marginal rows of sprocketfeed perforations 6 in oppositely directed edge strips 7, closely adjacent parallel rows of spaced longitudinally extending severance perforations 8, by means of which said selvages or laterally opposite marginal strips 7 are ultimately removed, a third longitudinal row of similar perforations 9 spaced slightly inwardly from one of said first longitudinal rows, by which the intervening strip area 10 of the finished envelope is removed by the addressee upon receipt from the sender, and for the purpose of removing its contents, and finally properly spaced transversely extending severance perforations 11 by means of which the individual frontal panels, following attachment to the corresponding lower panels, are separated to provide the separate finished envelopes.

From between the perforating rolls 4 and 5 said web passes between a printing roll 11 and a platten roll 12, by which in cooperation the upper outer face of said web is printed to include any desired indicia, but in this particular instance is represented for purposes of illustration as effecting the printing of a given return address 13, a stamp-indicating rectangle, frank, or other desired imprint 14, and also if desired simple directions such as the arrow 15 for instructing the ultimate addressee how and where to open the envelope to expose its contents for removal, which in this instance is along the secondmentioned perforated line 9. These functionally separate and independent perforating and printing operations may be substantially simultaneous or concurrent, but are here spaced well apart to aid in illustrating the various steps in the improved method of production. In Fig. 2 is shown a plan view of the roll 4 by which preferably circular and rule dies 16 and 17 are used to effect the circular sprocket-feed perforations 6, and the three parallel longitudinal rows 8 and 9, by which the individual envelopes are separated from one another, and from the marginal strips 7, and still later from individual opening strips 10. From the operations or steps thus described, said web 1 is fanfolded by any well known type of machine (not shown), and discharged therefrom in fanfold form 18 upon any suitable support 19.

While the upper web 1 is being thus treated, or previously or supplementary thereto, a second web 20 unwinds from its original roll 21, and after passing an idler 22, passes between a pair of perforating rolls 23 and 24, by which said latter web is provided in its narrow marginal strip portions 25 with sprocket-feed perforations 26, closely adjacent parallel rows of spaced longitudinally extending perforations 27, by means of which said marginal portions or strips 25 are ultimately removed; also a third row of longitudinal perforations 28, spaced slightly inwardly from and parallel with one of said first longitudinal rows, by which the intervening area 29 of the finished envelope is removed by the addressee; also properly spaced transverse rows of perforations 3 by means of which the individual panels, following attachment to the corresponding frontal panels are separated to provide the finished envelopes. Thus in the two webs, the sprocket perforations 6 and 26 correspond and register with other, when said webs are later brought together, the rows of perforations 8 corresponding and registering with the rows 27, the row 9 with the row 28, and the transverse rows 11 with the rows 30.

This second web passes from its perforating rolls between a printing roll 31 and a platten roll 32, by which in cooperation each envelopes final outer face is printed if desired to include any suitable indicia, such for example as the advertising matter 33. As with the first web, these functionally separate and independent perforating and printing operations may be substantially simultaneous or concurrent, but as in the first case are here spaced apart to better illustrate the various steps in the improved method of production. From the perforating and printing operations thus described, said web 20 is also fanfolded by any well known machine, (not shown), and discharged therefrom as at 34 upon any suitable support 35. The perforating roll 23 is similar to the corresponding roll 4, which is illustrated in Fig. 2.

Having the two separate piles of fanfolded webs 18 and 34, they are taken from their initial supports, or from other available supports 36 and 37 and fed into another machine by which they are united. This machine is represented by Figs. 4-6. Here the upper web 1 is led beneath an idler 38 and between an adhesive-applying roll 39 and a rotary platten 40. From an adhesive reservoir 41 and through a spreader 42, ordinary adhesive of any desired kind is applied to the longitudinal and transverse applying surfaces 43 and 44 of a distributing roll 45 by which said adhesive is applied to the strip area and to a corresponding strip area 46 inwardly of the perforations 8, and also to transverse strip areas 47 upon the forward side of the respective transverse lines of perforations 11, said web being propelled by a suitable sprocket wheel in engagement with the sprocket perforations 6 in well known manner.

While this operation is taking place relative to the first web 1, a somewhat similar operation is taking place with regard to the second web 20, which upon being drawn from its initial fanfold stack 34 passes over an idler roll 48, and thence through a roughly U-shaped path reversely about a relatively large roll 49 having spaced transverse raised surfaces 50, being kept in constant uniformcontact with said surfaces for a relative extended period by a pair of idlers 51 and 52, between which above the applying roll 49 is a spreader roll 53, which receives a suitable thermosetting adhesive from a reservoir 54 through a suitable discharge nozzle 55. The applicator roll surfaces 50 deposit the thermosetting material in spaced transverse strips 56 immediately. in advance of the transverse perforations 30, and after drying rapidly as said second web passes first beneath a weighted or spring-tensioned roll 57, this second web 20 passes upwardly around an idler roll 58, while the first-mentioned web 1 passes downwardly over a corresponding idler roll 59, from which idler rolls said webs converge and together pass between a pair of similar pressure rolls 60, by which they are united to form a continuous series of envelope units with their ordinary adhesive areas united and the combined webs then being again fanfolded together and led to a pile 61 upon a suitable support 62.

This pile of series-connected envelopes in fanfold relation is then placed upona support 63 in an addressing machine, such as is represented by Fig. 7, whence beginning with the uppermost envelope section of such series, they pass over an idler 64 against which they are held in frictional engagement by suitable means 65, which device serves to hold the doubled-web series taut as it passes around a platten roll 66, at which point the successive envelopes of the series have the addresses 67 printed upon them by any suitable means represented by the member 8. From this operation, said series passes through a trimmer 69, that serves to remove from the central body portion of the series the laterally opposite marginal edge portions 7 that carry the sprocket-receiving apertures 6, which up to this time have functioned with suitable sprocket wheels to propel the webs alone and subsequently the double-web series through the several successive steps or operations. Said addressed series is then again fanfolded in similar manner as heretofore and made to form a fresh pile 70.

This last-mentioned pile is then placed in a bursting machine, where its envelope sections in series pass between relatively slow-moving retarding tension rolls 71, while a short distance beyond these tension rolls said envelope sections are caught by and between relatively faster moving separator rolls 72, which serve to quickly separate each envelope section in turn along the perforations 11, and pile them as completely independent envelopes at 73. From this pile the individual envelopes between oppositely positioned, vertically spaced suction surfaces 74 and 75 (Fig. 10) by which the upper or front panel 75 is lifted upwardly, while the lower or rear panel 77 is held down, and a thin metal tongue 78 is inserted temporarily, so that the envelope can be stuffed or filled with whatever bills, circulars, or the like, may be de sired, without the filling snagging upon the lower envelope edge, after which said tongue is withdrawn and the envelope passes longitudinally between a lower roll or platen 79 and an upper heated pressure roll 84) (Figs. 11 and 12), by which the hitherto open normally upper edges of the envelope are heat-sealed, as said upper roll is suitably heated electrically and effects a softening and sealing of the thermoplastic strip 56.

The separated envelopes 81 that are now filled, ad-

dressed and sealed, are automatically stacked upon the pile 82, are ready for mailing, and following receipt by the respective addressees in the form shown in Fig. 13, are opened as indicated in Fig. 14 by removing from them the marginal strip 83 on one end, that comprises the combined initial strips 7 and 25 (Figs. 2 and 3). The heating of the roll may be accomplished in any suitable manner, but if heated electrically as suggested by the current source 84, the proper temperature can be controlled automatically to a fine degree.

Referring to composite Fig. 15, a partially modified method is here shown in which previously perforated upper end lower webs 1 and 20 have been perforated in any suitable manner, as for example by the mechanisms diagrammatically illustrated in Figs. 1, 2 and 3. These webs are initially in their respective fanfolded piles or stacks 18 and 34. From the pile 18 the upper web is led over an idler roll 85 towards and between a pair of compression rolls 86 and 87, where it is united with the lower web, which upon leaving its initial pile 34 passes over an idler roll 88 and thence through a roughly U- shaped path reversely about a relatively large roll 89, having spaced transverse raised surfaces 90 connected at their opposite ends by longitudinally extending raised surfaces 91, said web being kept in uniform contact with said surfaces for a relatively extended period by a pair of idlers 92 and 93, between which and above said applying roll 89 is a spreader roll 94, which receives a suitable thermosetting adhesive from a reservoir 95 through a suitable discharge nozzle 96.

Said applicator roll surfaces 90 and 91 deposit the thermosetting material upon spaced transverse strips 97, and also upon parallel marginal strips 98 immediately within the sprocket-perforated marginal edge strips 99, the said transverse strips 97 being wide enough and so arranged as to be upon both sides of each of the transverse rows of severing perforations 100. From the idler roll 93 said web 20 passes beneath a weighted or springpressed idler roll 101 and preferably another idler roll 102, whence said web unites with the first web 1 between said compression rolls 86 and 87 previously referred to. Continuing thence in unison, the twin or composite double web passes around an idler roll 103, reversely through an inverted, substantially U-shaped path about another relatively large roll 104, and then about a second idler roll 105, beneath another weighted or spring-pressed idler roll 106, and between a pair of compression rolls 107 and 108, to a fanfolded pile 109.

The large roll 104 is provided with a pair of longitudinally extending raised surfaces 110, connected by spaced transversely extending raised surfaces 111, and as said large roll is electrically heated by current from a suitable source 112, those strip areas of said double web against which said heated surfaces are pressed become firmly secured together through said thermosetting medium. This is aided by maintaining constant pressure of said web against said surfaces by means of a movable platten 113, which follows the curvature of said heated roll by means of a series of idler rolls 114, the desired tension being applied to said platten by means of a weighted or spring-pressed roll 115. It will be noted that the thermosetting adhesive, that is set by the heated roll 104- through its raised surfaces and 111, permanently secures together the laterally opposite end strip areas 116 immediately within the sprocket-perforated marginal strip portions 99, and only those portions 117 of the transverse strips 97, that are forwardly of the severance perforations 100, and which thereby seal What will eventually be the bottom edges of the finished envelopes after they are bursted or separated from one another, as before described.

Referring to Figs. 16-18, a slight modification is shown as providing an envelope of the so-called penny-saver, or postage saving, class. In this case, the roll 89 of Fig. 15 is replaced by a roll 118, which is characterized by a plurality of circumferentially spaced, longitudinally extending raised ridges or surfaces 119, connected together at one end only by a circumferentially extending raised surface 120, while in lieu of a second such connecting surface there are provided a series of spaced, radially directed fingers 121 of the same height as said ridges, and by means of which an adhesive that never dries, such as a latex derivative from a suitable reservoir 122 is deposited by a narrow spreader roll 123 upon similarly spaced abbreviated areas 124 of the lower web panel 211', while either thermosetting or musilaginous adhesive is being deposited upon the raised surfaces 119 and from a reservoir 125 through a spreader roll 126. When the two plies are then brought together, and

the strips having adhesive deposited by and from the raised surfaces 119 and 120 are secured together, their otherwise open end at the left (Figs. 16-18) is temporarily closed by the adhesion of the upper or frontal panel to the lower or rearward panel through the spots 124 of yielding adhesive deposited by the finger-like projections 121. This semi-permanent adhesion is sufficient to remain intact as long as necessary, but is capable of being separated as for postal inspection without tearing or otherwise mutilating the envelope, and the adhesion then being restored by simply pressing the two panels together over the particular area of the dots.

Referring to Figs. 19-21, the modified method here shown involves the initial use of two individual webs and 131 concurrently unwinding from their respective rolls 132 and 133, and each web passing in uniform surface contact with one of a pair of similar applicator rolls 134, that receive polyethylene from suitable reservoirs 135 through spreader nozzles 136. Polyethylene is applied in well known manner at a temperature of the order of 275 to 325 F., for which purpose each of said reservoirs and said spreader rolls is automatically maintained in heated condition, the polyethylene being thereby applied evenly to the entire adjacent surfaces of said webs, where it rapidly cools, sets and forms a moistureor water-proof coating, that especially adapts finished envelopes to use in damp or humid atmospheres, such as characterize transocean shipping, and thereby protect the contents against harm from this and similar conditions.

It should be understood that for the sake of simplicity and to prevent confusion and possible misunderstanding of the essential differences between this method and those hereinbefore described, the steps of perforating and sprocket-punching, printing, folding, addressing, bursting,

stuffing and sealing are omitted from Fig. 19, but it is to be understood that such steps are to be understood as occurring therein, as in the methods hereinbefore described. A great difference between this method and the others disclosed herein lies in the fact, that the entire areas of the adjacent surfaces of the two envelope panels are potentially adhesive, but adhere to each other only when and as longitudinally extending, marginal strips 137 and longitudinally spaced, transversely extending strips 138 are heated to the proper temperature, while passing between the heat and platen rolls 139 and 140,

the, former of which is provided with longitudinal raised surfaces 141 and similar transverse connecting surfaces 142, which receive heat through suitable conductors from a convenient source 143, and soften both of the two ad-. jacent layers of polyethylene between them and the surface of said platen roll, and simultaneously press them together in intimate binding relation, so that they adhere to each other and form a permanent seal along what becomes the two laterally opposite edges and the normal bottom edge of the final envelope, after it is severed or bursted from its adjacent envelope units along the previously perforated lines 144. Envelope units thus prepared are printed as desired, have stripped from them the marginal sprocket-perforated edge portions, bursted, stuffed, and finally sealed for mailing, by having their normally upper open edge portions 145 sealed by and as they pass between an electrically heated roll 146 and a platten roll 147 (Figs. 20 and 21).

Referring to Figs. 22 and 23, a web 150 is here shown as being unwound from a roll 151, and then passed between a pair of perforating rolls 152 and 153, then between a printing roll 154 and a rotary platten 155, then over a glue-applying roll 156 below a rotary platten 157, after which said web is folded transversely at 158 about its central line of fold-defining perforations, and beneath a pair of pressure rolls 159 and 160, by which the new parallel half-webs are secured together along the strips of glue or other adhesive, as hereinbefore described. This resulting double-thick web 161 is then printed, bursted or separated from its fellows, filled or stuffed, and sealed, as hereinbefore described.

The original web 150 is provided with a central line of fold-defining perforations 162, and slightly spaced upon the opposite sides thereof with parallel rows 163 of severance perforations, to provide marginal strips 165, in each of which is a row of sprocket perforations 166. The laterally opposite edge portions of said web are provided with rows of severance perforations 167 and two marginal rows of sprocket perforations 168, while still another row of longitudinal severance perforations 169 are provided; also longitudinally spaced transverse rows 170. The adhesive is applied by a roll such as is shown in Figs. 4 or 15 to provide roughly U-shaped adhesive strips by which the laterally related web sections are united, the same as the two initially separate and independent webs hereinbefore described. There are also provided strips 171 of a preferably thermosetting medium, by which when properly heated effect the sealing of the initially open top edges of the envelopes for mailing. It will be understood that following the uniting and securing of the two Web sections together, as shown in Fig. 22, the resulting double web has its respective envelope units addressed, bursted or separated, filled of stuffed, and then sealed as hereinbefore described and as indicated in such arrangements as are illustrated in Figs. 7 to 13, and thus made ready for mailing and subsequent opening by the addressee as indicated in Fig. 14. In this manner is provided and envelope that is adapted for great mass production, and as an alternative method relative to early details in its production compared with the first and later described methods, one or another of which may lend itself better to existing production machinery than do the others.

Having thus described my invention, what I claim and desire to protect by Letters Patent of the United States is:

The method of making and sealing an envelope, which consists in perforating the laterally opposite marginal portions of a pair of webs to receive the sprockets of a propelling mechanism, also perforating said webs longitudinally within said sprocket perforations for later severance of said marginal portions from the body portions of said webs, providing in said webs a second line of longitudinal severances in spaced relation inwardly of one of said first such perforations to provide an envelopeopening strip, providing longitudinally spaced transverse severance perforations in said webs corresponding with the bottom edges of the final envelope units, applying to said first web adhesive adjacent to and forwardly of said transverse perforations and also along strip a'reas im- 10 edges of each envelope together and efiect a sealing of their adjacent adhesive strip areas, said envelopes being thereafter opened by removing from one end of each envelope said opening-strip which is partially separated mediately inside of said sprocket-perforated marginal por- 5 by said second line of longitudinal perfora ions.

tions, applying a second adhesive medium to transverse strip areas of the second web adjacent to and rearwardly of the location of the corresponding transverse strip areas of adhesive on said first web, bringing said webs together so that the first adhesive secures together corresponding roughly U-shaped strip areas forwardly of the now registering rows of transverse perforations of said webs, removing the sprocket-perforated marginal portions of the combined webs, separating the resulting envelopes along said transverse perforations, and bringing the open top 15 2,699,098

References Cited in the file of this patent UNITED STATES PATENTS 1,714,265 Gurwick May 21, 1929 2,102,001 Heywood Dec. 14, 1937 2,342,702 Sherman Feb. 29, 1944 2,363,417 Heywood Nov. 21, 1944 2,474,775 Borchers June 28, 1949 Lyons Jan. 11, 1955 

